Seeking to avoid a “quarterback controversy” at first base, the Padres Friday morning moved first base prospect Anthony Rizzo to the Chicago Cubs for right-handed power pitcher Andrew Cashner.

Cashner and Rizzo are the featured players in a four-player trade.

The Padres got the 25-year-old Cashner and 20-year-old South Korean center fielder Kyung-Min Na in exchange for Rizzo and right-handed starter Zach Cates, who was the Padres third-round pick in the 2010 draft.

Cashner, whose fastball has been clocked at 100 mph, will be used as a “toward the end of the game” reliever in 2012, although the Padres believe his future could be in the rotation or as a closer.

He is a candidate this season for the eighth-inning setup role in front of closer Huston Street.

There is a risk with Cashner, who missed most of the 2011 season with a strained rotator cuff.

“Andrew’s potential is extremely exciting,” said Padres manager Bud Black. “This is a big, power arm with some upside. He has great numbers on the radar gun and a solid delivery. He has a strong fastball, a hard slider and a change. He projects in the future in several roles.”

Trading Rizzo came in the wake of the Padres acquiring first baseman Yonder Alonso as part of the Mat Latos trade on Dec. 17.

Hoyer, of course, traded for Rizzo 13 months ago as the Padres general manager, acquiring the first baseman and right-handed starting pitcher Casey Kelly as the top prospects among four players coming from Boston for first baseman Rizzo.

Many Padres fans reacted angrily Friday, believing the Padres didn’t get enough for Rizzo from the Cubs or for Gonzalez from the Red Sox.

Once regarded as the top prospect in the Padres organization, the 22-year-old Rizzo had a roller-coaster season last year between Triple-A Tucson and the Padres and was recently dropped to No. 2 behind Alonso at first base on the Padres depth chart.

Hoyer, meanwhile, retained a strong belief in Rizzo’s credentials – having first drafted Rizzo while an assistant GM in Boston then acquiring him for the Padres.

“Having both Alonso and Rizzo in spring training would have been a little like having a quarterback controversy,” said Byrnes after he completed his fourth major trade in a month and his seventh since succeeding Hoyer as the Padres general manager in October.

“We didn’t want that and we felt that Alonso might fare a little better at Petco Park. The acquisition of Alonso provided us the flexibility to make this trade and acquire a quality, young power arm in Cashner.”

A left-handed power-hitter, Rizzo was quickly identified by Hoyer as the “Padres’ first baseman of the future” after being acquired from Boston on Dec. 6, 2010.

Rizzo immediately turned heads with Triple-A Tucson and hit .331 overall with 26 homers and 101 RBI in 93 games in the Pacific Coast League. But he struggled when he was first promoted to the major leagues on June 9 and batted .141 with one homer and nine RBI in 49 total games in two stints with the Padres. He had 46 strikeouts in 128 at-bats while struggling with a long swing. Rizzo also drew 21 walks.